package com.yt.util;


import java.io.UnsupportedEncodingException;

/**
 * 转换字符串的编码
 */
public class ChangeCharset {
	
	/** GB2312 */
	public static final String GB2312 = "GB2312";
	/** 7位ASCII字符，也叫作ISO646-US、Unicode字符集的基本拉丁块 */
	public static final String US_ASCII = "US-ASCII";

	/** ISO 拉丁字母表 No.1，也叫作 ISO-LATIN-1 */
	public static final String ISO_8859_1 = "ISO-8859-1";

	/** 8 位 UCS 转换格式 */
	public static final String UTF_8 = "UTF-8";

	/** 16 位 UCS 转换格式，Big Endian（最低地址存放高位字节）字节顺序 */
	public static final String UTF_16BE = "UTF-16BE";

	/** 16 位 UCS 转换格式，Little-endian（最高地址存放低位字节）字节顺序 */
	public static final String UTF_16LE = "UTF-16LE";

	/** 16 位 UCS 转换格式，字节顺序由可选的字节顺序标记来标识 */
	public static final String UTF_16 = "UTF-16";

	/** 中文超大字符集 */
	public static final String GBK = "GBK";

	/**
	 * 将字符编码转换成US-ASCII码
	 */
	public String toASCII(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, US_ASCII);
	}

	/**
	 * 将字符编码转换成ISO-8859-1码
	 */
	public String toISO_8859_1(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, ISO_8859_1);
	}

	/**
	 * 将字符编码转换成UTF-8码
	 */
	public String toUTF_8(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, UTF_8);
	}

	/**
	 * 将字符编码转换成UTF-16BE码
	 */
	public String toUTF_16BE(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, UTF_16BE);
	}

	/**
	 * 将字符编码转换成UTF-16LE码
	 */
	public String toUTF_16LE(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, UTF_16LE);
	}

	/**
	 * 将字符编码转换成UTF-16码
	 */
	public String toUTF_16(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, UTF_16);
	}

	/**
	 * 将字符编码转换成GBK码
	 */
	public String toGBK(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, GBK);
	}
	
	/**
	 * 将字符编码转换成GB2312码
	 */
	public String toGB2312(String str) throws UnsupportedEncodingException {
		return this.changeCharset(str, GB2312);
	}

	/**
	 * 字符串编码转换的实现方法
	 * 
	 * @param str
	 *            待转换编码的字符串
	 * @param newCharset
	 *            目标编码
	 * @return
	 * @throws UnsupportedEncodingException
	 */
	public String changeCharset(String str, String newCharset) throws UnsupportedEncodingException {
		if (str != null) {
			// 用默认字符编码解码字符串。
			byte[] bs = str.getBytes();
			// 用新的字符编码生成字符串
			return new String(bs, newCharset);
		}
		return null;
	}

	/**
	 * 字符串编码转换的实现方法
	 * 
	 * @param str
	 *            待转换编码的字符串
	 * @param oldCharset
	 *            原编码
	 * @param newCharset
	 *            目标编码
	 * @return
	 * @throws UnsupportedEncodingException
	 */
	public String changeCharset(String str, String oldCharset, String newCharset) throws UnsupportedEncodingException {
		if (str != null) {
			// 用旧的字符编码解码字符串。解码可能会出现异常。
			byte[] bs = str.getBytes(oldCharset);
			// 用新的字符编码生成字符串
			return new String(bs, newCharset);
		}
		return null;
	}
	/**
	 * 描述：Unicode  >>>  中文
	 * @param theString
	 * @return
	 * @author lizheng
	 * @date 2017年9月6日
	 */
	public static String decodeUnicode(String theString) {    
        char aChar;    
        int len = theString.length();    
        StringBuffer outBuffer = new StringBuffer(len);    
        for (int x = 0; x < len;) {    
            aChar = theString.charAt(x++);    
            if (aChar == '\\') {    
                aChar = theString.charAt(x++);    
                if (aChar == 'u') {    
                    // Read the xxxx    
                    int value = 0;    
                    for (int i = 0; i < 4; i++) {    
                        aChar = theString.charAt(x++);    
                        switch (aChar) {    
                        case '0':    
                        case '1':    
                        case '2':    
                        case '3':    
                        case '4':    
                        case '5':    
                        case '6':    
                        case '7':    
                        case '8':    
                        case '9':    
                            value = (value << 4) + aChar - '0';    
                            break;    
                        case 'a':    
                        case 'b':    
                        case 'c':    
                        case 'd':    
                        case 'e':    
                        case 'f':    
                            value = (value << 4) + 10 + aChar - 'a';    
                            break;    
                        case 'A':    
                        case 'B':    
                        case 'C':    
                        case 'D':    
                        case 'E':    
                        case 'F':    
                            value = (value << 4) + 10 + aChar - 'A';    
                            break;    
                        default:    
                            throw new IllegalArgumentException(    
                                    "Malformed   \\uxxxx   encoding.");    
                        }    
        
                    }    
                    outBuffer.append((char) value);    
                } else {    
                    if (aChar == 't')    
                        aChar = '\t';    
                    else if (aChar == 'r')    
                        aChar = '\r';    
                    else if (aChar == 'n')    
                        aChar = '\n';    
                    else if (aChar == 'f')    
                        aChar = '\f';    
                    outBuffer.append(aChar);    
                }    
            } else    
                outBuffer.append(aChar);    
        }    
        return outBuffer.toString();    
    }
	public static void main(String[] args) throws UnsupportedEncodingException {
		ChangeCharset test = new ChangeCharset();
		String str = "This is a 中文的 String!";
		System.out.println("str: " + str);
		String gbk = test.toGBK(str);
		System.out.println("转换成GBK码: " + gbk);
		System.out.println();
		String ascii = test.toASCII(str);
		System.out.println("转换成US-ASCII码: " + ascii);
		gbk = test.changeCharset(ascii, ChangeCharset.US_ASCII, ChangeCharset.GBK);
		System.out.println("再把ASCII码的字符串转换成GBK码: " + gbk);
		System.out.println();
		String iso88591 = test.toISO_8859_1(str);
		System.out.println("转换成ISO-8859-1码: " + iso88591);
		gbk = test.changeCharset(iso88591, ChangeCharset.ISO_8859_1, ChangeCharset.GBK);
		System.out.println("再把ISO-8859-1码的字符串转换成GBK码: " + gbk);
		System.out.println();
		String utf8 = test.toUTF_8(str);
		System.out.println("转换成UTF-8码: " + utf8);
		gbk = test.changeCharset(utf8, ChangeCharset.UTF_8, ChangeCharset.GBK);
		System.out.println("再把UTF-8码的字符串转换成GBK码: " + gbk);
		System.out.println();
		String utf16be = test.toUTF_16BE(str);
		System.out.println("转换成UTF-16BE码:" + utf16be);
		gbk = test.changeCharset(utf16be, ChangeCharset.UTF_16BE, ChangeCharset.GBK);
		System.out.println("再把UTF-16BE码的字符串转换成GBK码: " + gbk);
		System.out.println();
		String utf16le = test.toUTF_16LE(str);
		System.out.println("转换成UTF-16LE码:" + utf16le);
		gbk = test.changeCharset(utf16le, ChangeCharset.UTF_16LE, ChangeCharset.GBK);
		System.out.println("再把UTF-16LE码的字符串转换成GBK码: " + gbk);
		System.out.println();
		String utf16 = test.toUTF_16(str);
		System.out.println("转换成UTF-16码:" + utf16);
		gbk = test.changeCharset(utf16, ChangeCharset.UTF_16LE, ChangeCharset.GBK);
		System.out.println("再把UTF-16码的字符串转换成GBK码: " + gbk);
		String s = new String("中文".getBytes("UTF-8"), "UTF-8");
		System.out.println(s);
	}
}
